As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Some information handling systems, such as laptop computer systems, have the ability to utilize one or more batteries as a power source. In addition, these same systems can also often utilize power obtained through a power converter coupled to a power grid, such as an alternating-current-to-direct-current (AC/DC) converter plugged into a wall socket. When the system is plugged into the wall, the battery in the system can be charged at the same time. As battery technology has improved, batteries have become more intelligent in that they include circuitry to manage their operations and to report conditions about the battery operations to external circuitry, such as microprocessors. These intelligent batteries are often called “smart” batteries. Many smart batteries have the ability to monitor the charging process, and many batteries have failure detection mechanisms to determine when the battery is malfunctioning. To protect users, the smart batteries can be configured to deactivate themselves permanently if a dangerous malfunction has been detected.
Certain current battery packages rely upon a charge field-effect-transistor (C-FET) and a discharge FET (D-FET) to control the normal charge and discharge function of the battery. Battery protect is typically governed by the battery management unit (BMU). In the event of a battery system failure detection (such as over-voltage charging or overloading) or a battery cell failure detection, the BMU in prior these battery systems would either temporarily disable the C-FET and D-FET to disconnect the battery from the system or permanently disable the battery by blowing a disable fuse.
One significant problem associated with this BMU operation is the possibility that a battery will be disabled due to a false detection of a battery failure. This false detection can lead to significant numbers of field returns of operational batteries that have been disabled due to false failure detections. For example, a false detection of a battery failure can often be the result of temporary environmental events, such as strong electro-magnetic interference (EMI), radio-frequency (RF) signals and/or other electro-magnetic (EM) influences, that cause a small charging current to be detected when none is supposed to exist, such as when the battery is in sleep or discharge mode. When the BMU detects a charging current that was supposed to be zero in such circumstances, the BMU will often place the battery into permanent failure mode due to this non-zero condition being deemed a critical protection failure. A charging current when no charging current should exist is often associated with an internal battery failure that could cascade into a catastrophic event, such as a battery short or explosion. As such, the BMU will disable the battery to protect the user. However, if the current were due to a temporary EM event as described above, the disabling of the battery would be unnecessary.
To address this problem, prior battery systems have attempted various solutions. One solution is to increase the current protection threshold for when an improper charging current will be deemed to trigger a possibility for catastrophic failure. Another solution is to extend the response time from the time when battery initially detects this problem to the time battery BMU finally decides to put the battery to permanent failure mode. Both of these solutions reduce the chance that the battery will be disabled due to EM influences. However, although these solutions do improve battery performance, these solutions also sacrifice safety protections.
Another proposed solution is to add a switch in the battery charging and discharging path and to detect the amount of time an abnormal current lasts. With the added switch turned off, if an abnormal current goes away within a preset time limit, which can be BIOS controlled, the failure can be considered to be temporary. In this circumstance, the battery will not be permanently disabled, and the added switch will be turned on again. This solution, however, has cost and power disadvantages. In particular, this solution increases the cost of the battery pack by requiring an additional switch and increases power dissipation inside the battery thereby increasing internal pack temperatures and reducing the battery capacity available to the system.